Earth

Cradle of Life As We Know It

Earth is the only place we know of in the universe that harbors life. Ours is the largest terrestrial planet in the solar system. Our rocky, volcanic world is coated in a thin veneer of liquid water, living things, and translucent atmosphere, whose complicated interactions make Earth's surface into a place of constant change. We humans have only had fifty years of perspective on Earth as a planet, of seeing it as a "pale blue dot" floating in the black vacuum of space.

With that perspective, we know precious and unique our planet is. We know, too, that we are having measurable effects on the complex interactions of ocean, land, life, water, and air, changing our climate. But predicting the future of our climate is hard. Understanding how Earth's systems work by studying the way they operate on other worlds is a major goal of planetary exploration. Mars, Venus, and Titan all have (or had) active geology, hydrology, and weather -- but, as far as we know, they don't have life. Is Earth really that unique? Are we truly alone in the universe? We won't know unless we keep searching.

News from Earth

After entering safe mode last week during its Earth flyby, Juno returned to normal operations and downlinked all engineering and science instrument data. It entered safe mode again on Sunday night, but it is expected to re-resume normal operations late next week.

As of November 2011, the Earth Observing Handbook counts 109 active missions to study the Earth as a planet, with 112 more approved and planned for the future. Jason Davis provides an overview of key current and upcoming earth-observing missions.